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serpa4
Joined: 13 Nov 2022 Posts: 86 City/Region: Melbourne
State or Province: FL
C-Dory Year: 2018
C-Dory Model: 26 Venture
Vessel Name: DayLo
Photos: DayLo
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Posted: Tue Apr 04, 2023 7:52 am Post subject: How to get real MPG? |
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Yes, I know how to do it. Easy.
But what is the best way in a boat?
I assume fill up at a dock so that the boat is "Level". Run at my desired cruise for say 50 miles. Far enough to use a measurable amount of fuel. Doesn't do much to go use 1/2 gallon and then the variation in filling up could be 1/2 gallon.
When done, fill up at the same marina.
So, what is the best way to measure distance? Phone w/gps? Boats chart plotter?
Then filling up at the marina, I would like to totally top it off. That may mean some back flows and burps a lot to get a perfectly full tank. I'm sure they won't like that. I don't think that filling it up till it stops then say 2 more clicks etc is very accurate.
From what I have read, my MPG is too high. 2018 Venture/200hp suzuki, 100% full of fuel and water, packed for a trip.
RPM / MPH / MPG off suzuki dedicated MFD.
1500 / 8.18 / 4.8
2000 / 9.56 / 3.87
2500 / 14.3 / 4.36
3000 / 17.6 / 4.28
3500 / 22.9 / 3.58
4000 / 26 / 3.25
4500 / 30 / 2.54
Did not do WOT or go over 30mph. _________________ 2018 C-Dory Venture 26. Suzuki DF200A,autopilot, solar, 412ahr of lithium. |
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baref00tin
Joined: 14 Mar 2023 Posts: 5 City/Region: Deltona
State or Province: FL
C-Dory Year: 2002
C-Dory Model: 16 Cruiser
Vessel Name: COUPE SEA VILLE
Photos: COUPE-SEA-VILLE
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Posted: Tue Apr 04, 2023 8:35 am Post subject: |
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I would say the best way to measure your engine performance is to make sure you have equipment that supports NMEA2000 and install a gateway to connect the two. This will give you real time engine stats and performance. |
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C-Wolfe
Joined: 16 Sep 2020 Posts: 259 City/Region: Anchorage
State or Province: AK
C-Dory Year: 2008
C-Dory Model: 255 Tomcat
Vessel Name: Valhalla
Photos: C-Wolfe
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Posted: Tue Apr 04, 2023 12:38 pm Post subject: |
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You could use portable tank where you can much more accurately measure your fuel consumption. I have a 12G that I sometime carry to give me extra range that I can connect directly to my fuel filter/water separator. So far I did it once, I started a track on my chart plotter outside the harbor on a run I knew I will burn more then 12 G in one go. I switch to the portable tank and ran the boat until I run out of gas, stop the track and did the math. Calm day, light load I do a bit over 4 MPG at 20 MPH, I should do it again since I never go out on such a light load. _________________ Stephan
ValHalla 08 TC255 2024-present
C-Wolfe 22 C-Dory cruiser 2020-24
No Name; Bayliner explorer 26 2012-2015
sparkle; Ericson 25 CB 2008-2012
Sculpin; Drascombe Drifter 2005-2008 |
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ssobol
Joined: 27 Oct 2012 Posts: 3386 City/Region: SW Michigan
State or Province: MI
C-Dory Year: 2008
C-Dory Model: 22 Cruiser
Vessel Name: SoBELLE
Photos: SoBelle
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Posted: Tue Apr 04, 2023 1:17 pm Post subject: Re: How to get real MPG? |
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serpa4 wrote: | Yes, I know how to do it. Easy.
But what is the best way in a boat?
I assume fill up at a dock so that the boat is "Level". Run at my desired cruise for say 50 miles. Far enough to use a measurable amount of fuel. Doesn't do much to go use 1/2 gallon and then the variation in filling up could be 1/2 gallon.
When done, fill up at the same marina.
So, what is the best way to measure distance? Phone w/gps? Boats chart plotter?
Then filling up at the marina, I would like to totally top it off. That may mean some back flows and burps a lot to get a perfectly full tank. I'm sure they won't like that. I don't think that filling it up till it stops then say 2 more clicks etc is very accurate.
From what I have read, my MPG is too high. 2018 Venture/200hp suzuki, 100% full of fuel and water, packed for a trip.
RPM / MPH / MPG off suzuki dedicated MFD.
1500 / 8.18 / 4.8
2000 / 9.56 / 3.87
2500 / 14.3 / 4.36
3000 / 17.6 / 4.28
3500 / 22.9 / 3.58
4000 / 26 / 3.25
4500 / 30 / 2.54
Did not do WOT or go over 30mph. |
Doesn't matter that you fill the tank completely, just that you fill it the same way twice (before and after the run).
Also, as you add fuel, the attitude of the boat is going to change. If you're level with a low tank, you won't be will a full one. You also have to pay attention to lateral attitude.
At best you are only going to get a reasonable approximation of the MPG. The current. wind. tides, waves are always changing and your MPG will only be accurate for the conditions of the trial. Your boat MPG also improves as fuel burns off.
I have a FF meter on my boat that computes the remaining range. After some exeperience, I use 3 mpg for trip planning purposes. The boat gets greater MPG than that. But using 3 builds in a fuel reserve. |
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digger
Joined: 02 Nov 2003 Posts: 496 City/Region: Spokane
State or Province: WA
C-Dory Year: 1993
C-Dory Model: 22 Angler
Vessel Name: C-Sik
Photos: Snoopy-C
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Posted: Tue Apr 04, 2023 2:35 pm Post subject: |
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I have a floscan in-line with fuel line. Shows gallons per hour, and also records total gallons used (resettable). Keep track with gps miles covered and divide by gallons used. |
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jkidd
Joined: 23 Oct 2006 Posts: 1627 City/Region: Northern, Utah
State or Province: UT
C-Dory Year: 2007
C-Dory Model: 22 Cruiser
Vessel Name: Voyager
Photos: Voyager (JK)
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Posted: Tue Apr 04, 2023 3:50 pm Post subject: |
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You should be able to read it right off of the motors computer. All you need is a NMEA 2000 network and the Suzuki Digital gauge. It will read it right off of the fuel injection. Mine will be within a tenth of a gallon when I refill. It will give you gallons per hour flow, fuel remaining, mile per gallon, range to empty. You do have to have a way to read gps speed into the NMEA 2000 network. That can be done with a NMEA 2000 GPS antenna or reading it from an MDF display that has built in gps and NMEA 2000 builtin. _________________ Jody Kidd
KE7WNG
Northern, Utah
![](http://www.c-brats.com/albums/Voyager-JK/IMG_3505.jpg) |
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serpa4
Joined: 13 Nov 2022 Posts: 86 City/Region: Melbourne
State or Province: FL
C-Dory Year: 2018
C-Dory Model: 26 Venture
Vessel Name: DayLo
Photos: DayLo
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Posted: Tue Apr 04, 2023 5:12 pm Post subject: |
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jkidd wrote: | You should be able to read it right off of the motors computer. All you need is a NMEA 2000 network and the Suzuki Digital gauge. It will read it right off of the fuel injection. Mine will be within a tenth of a gallon when I refill. It will give you gallons per hour flow, fuel remaining, mile per gallon, range to empty. You do have to have a way to read gps speed into the NMEA 2000 network. That can be done with a NMEA 2000 GPS antenna or reading it from an MDF display that has built in gps and NMEA 2000 builtin. |
Has all that equipment already. But seems too good. I want to double check. |
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jkidd
Joined: 23 Oct 2006 Posts: 1627 City/Region: Northern, Utah
State or Province: UT
C-Dory Year: 2007
C-Dory Model: 22 Cruiser
Vessel Name: Voyager
Photos: Voyager (JK)
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Posted: Tue Apr 04, 2023 9:52 pm Post subject: |
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Show us a picture of your helm. |
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jkidd
Joined: 23 Oct 2006 Posts: 1627 City/Region: Northern, Utah
State or Province: UT
C-Dory Year: 2007
C-Dory Model: 22 Cruiser
Vessel Name: Voyager
Photos: Voyager (JK)
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Posted: Tue Apr 04, 2023 10:10 pm Post subject: |
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This is one of my gauges that I can change any of the fields on it to read anything on the NMEA 2000 network. This one can have 10 pages of info.
You can also configure your MFD to display the same info.
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Foggy
Joined: 01 Aug 2013 Posts: 1524 City/Region: Traverse City; Northern Lake Michigan
State or Province: MI
C-Dory Year: 2014
C-Dory Model: 26 Venture
Vessel Name: Boatless in Boating Paradise
Photos: W B Nod
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Posted: Wed Apr 05, 2023 10:29 am Post subject: |
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Micro-calculations for researching exact mpg on a perfect flat sea, known load,
etc is an interesting exercise leading to a possible disappointment. Day to day
differences in wind, sea state, current, load, even altitude at different locations
will be different from your carefully researched data, which, if followed precisely
for a specific trip, could make you come up short on fuel.
More practical is to know precisely where your fuel gauge(s) show an empty fuel tank.
Know this by running the tank(s) dry until your engine(s) stop and mark the
gauge(s) [or take/record a photo]. Refuel using mindfully anticipated jerry jug fuel.
Then used this time proven fuel macro-calculation for your daily nautical adventures:
1/3 of a tank to get there
1/3 of a tank to get back
1/3 of a tank for an emergency
Aye. _________________ "I don't want any cake" - said no one ever.
If someone tells you they don't eat cake, unfriend them. You don't need that kind of negativity in your life. |
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thataway
Joined: 02 Nov 2003 Posts: 20859 City/Region: Pensacola
State or Province: FL
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
Photos: Thataway
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Posted: Wed Apr 05, 2023 1:19 pm Post subject: |
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I have put in flow meters in almost all of my boats. Unfortunately all of their motors were too old to get the information off of the engine's computer.
Foggy gives you excellent advice. You need to know what your fuel flow is at that specific time and on the total of that run. There are so many variables, such has current, wind, tide and seas, which will make a large difference in your MPG or range.
Above is the fuel consumption of "Thataway" the C Dory 25 I last owned. it was made by a previous owner, but I confirmed that it was accurate. At 3000 RPM I was getting about 2.5 nmpg at 8 nautical miles per hour. At 17.5 statute miles per hour & 4500 RPM, I was getting about 3 statute miles per hour.
The numbers posted by serpa4 . seem a little off. I am not sure why, but something is wrong in the way they are being measured? Yes, different 4 stroke engines, different hulls, and conditions; but getting 4.28 mpg at 3000 RPM/& 17.6 miles per hour (I have to assume statute miles, not nautical). Is the boat super light-one person minimal fuel and water etc? The C Dory line are sensitive to weight, as well as windage. Is it possible that current or tail wind etc--or accidental nautical vs statute? How was the mileage measured? Generally with the 200 hp outboards the C Dory 25 gets slightly better mileage than the Venture 26--but it is pretty close.
The other factor is that you are getting 30 mph 4500 RPM, and we don't know your WOT either in RPM or speed. What is the loading of the boat? If these numbers are true--then very light boat, and perfect environmental conditions.
In these boats I have compared the fill up to fill up and they will agree with an average fuel consumption or total fuel used as measured by the flow meter. But it is not easy to get the exact level of fill up with each attempt. The other factor, is the way I boat, it would be a very difficult day to run 50 miles at a constant RPM and constant conditions. I can't think of many places where you can do this. _________________ Bob Austin
Thataway
Thataway (Ex Seaweed) 2007 25 C Dory May 2018 to Oct. 2021
Thisaway 2006 22' CDory November 2011 to May 2018
Caracal 18 140 Suzuki 2007 to present
Thataway TomCat 255 150 Suzukis June 2006 thru August 2011
C Pelican; 1992, 22 Cruiser, 2002 thru 2006
Frequent Sea; 2003 C D 25, 2007 thru 2009
KA6PKB
Home port: Pensacola FL |
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